Lift cycle assessment (LCA) methodology was applied to evaluating and comparing two waste acid disposal processes in zinc smelting. The results indicate that environmental impacts of gas-liquid vulcanization technologies are human toxicity, abiotic depletion potential, and global warming risk, which are mainly caused in neutralizing- evaporating-crystallization unit and electrodialysis unit. As for traditional lime neutralization method, vulcanization unit is the main factor. In this regard, the total environmental impact of traditional lime neutralization method is much higher than that of gas-liquid vulcanization technologies. Furthermore, the sensitive analysis shows that electricity and sodium sulfide (60%) are sensitive factors in two waste acid disposal technologies. In addition, the total cost of disposing a functional unit waste acid in traditional lime neutralization process is nearly 27 times that of the gas-liquid vulcanization waste acid disposal technologies.